1. Field of the Invention
The present invention relates to a magnetic recording and reproduction apparatus, more particularly a data recorder using a magnetic tape to perform a self-diagnostic function and a means for identifying the type (grade) of the magnetic tape mounted thereon.
2. Description of the Related Art
A data recorder as one component of a magnetic recording and reproduction apparatus (system) stores on a magnetic tape a variety of signals such as process signals, for example, temperature, humidity, pressure, level, and flow; digital signals, for example, switching positions; and relay contact positions, and digital data, for example, time and recording conditions. Several types of data recorders can be employed. In a first type of data recorder, analog data is input and stored on the magnetic tape. In a second type of data recorder, analog data is input converted to digital data, and stored on the magnetic tape. In a third type of data recorder, digital data is input and stored on the magnetic tape. In these data recorders, of course, the data stored on the magnetic tape can be reproduced. During this reproduction, equalization can be performed to provide discriminated reproduction signals at a high accuracy. The magnetic tape, preferably, may be accommodated in a cassette or a case like that of a cassette tape used for a video tape recorder (VTR).
Recently, there has been a strong demand for a self-diagnosis in such data recorders. As a result, self-diagnostic programs are being loaded in such data recorders. In such a self-diagnosis, a magnetic tape on which data adaptable for an electrical test is recorded (an electrical calibration magnetic tape), a magnetic tape on which data adaptable for a mechanical test is recorded (a mechanical calibration magnetic tape), or a magnetic tape on which no data is recorded (a blank magnetic tape) is mounted in the data recorder, and then a diagnostic operation is performed in accordance with the contents recorded on the electrical calibration magnetic tape, and/or the mechanical calibration magnetic tape.
In addition to the above magnetic tapes, in data recorders, a general purpose magnetic tape used for usual data recording, a cleaning magnetic tape used for cleaning the recording head and/or reproducing head, and other magnetic tapes can be used. Normally, those magnetic tapes are accommodated in cases (or cassettes), and the data recorded thereon is directly invisible, and therefore, the user can not know what kind of contents are recorded on the magnetic tape without a visual indication on the case.
Usually, self-diagnosis is not carried out frequently. The frequency may be, for example, once per two to three months or once per year. Therefore, the user of the data recorder is not well versed with the self-diagnostic method in many cases. As a result, for example, mistaken switching of the electrical calibration magnetic tape or the mechanical calibration magnetic tape with the cleaning tape in the data recorder and actuation of the self-diagnostic function when using the mounted cleaning tape may occur. In this case, the cleaning tape will polish the reproducing head and recording head for a long time to result in abrasion of the heads. Thus, serious damage to the reproducing head and recording head may occur.
Also, there is a possibility that the electrical calibration magnetic tape and the mechanical calibration magnetic tape will be erroneously mounted in the data recorder and a self-diagnostic function not corresponding to that magnetic tape will be actuated. As a result, the results of the self-diagnosis will become complete nonsense and irrespective of the fact that the data recorder is actually normal, the user will think that there is a malfunction. Alternatively, the inconvenience that the self-diagnosis must be carried out again occurs.
Furthermore, there is a possibility of the erroneous mounting of the electrical calibration magnetic tape or the mechanical calibration magnetic tape or general purpose magnetic tape on which important data has been recorded and actuation of the self-diagnostic function. When a general purpose magnetic tape is mounted and the self-diagnostic test is performed, i.e., data is recorded on the magnetic tape, then read out and verified, destruction of data recorded on the mounted general purpose tape may occur.
That is, in a conventional data recorder, human error is apt to occur at the self diagnostic test. When a magnetic tape not corresponding to the self-diagnostic function actuated in the data recorder as mentioned above is mounted in the data recorder, serious damage may be done to the reproducing head and recording head. Also, the results of the self-diagnostic test may become nonsense, so that a normal data recorder is believed to malfunction, or trouble occurs of data of the tape not related to the self-diagnostic test being destroyed.